1. Field of the Invention
This invention relates to a device for supporting the inner or primary pipe within an outer containment pipe of a double containment pipe system.
2. Background Information
Hazardous fluids cannot be routinely conveyed in open top drainage channels, but instead in enclosed pipes or conduits. Recognizing that such pipes and conduits can leak because of manufacturing defects, excessive pressure, corrosion or other reasons, the prior art has devised dual containment systems which generally involve the placement of a relatively small fluid carrying closed-wall conduit or pipe within a larger closed-wall conduit or pipe which does not carry fluids except in the event of a leak of liquid carried by the inner conduit. The smaller conduit or pipe is supported by resting directly on the lower, inner wall of the outer conduit or pipe. Alternatively, supports have been proposed wherein the inner pipe may be supported in spaced relation to the lower inner wall of the conduit or pipe. Examples of such supports are illustrated in U.S. Pat. Nos. 4,751,945; 3,863,679; and 3,417,785.
While such supports may be used to space the inner and outer pipes and provide ready access to the inner pipe as spaced locations along the outer pipe, the supports shown in the prior art do not lend themselves to adjustment of the location of the inner or primary pipe relative to the outer or containment pipe.
The support assembly disclosed herein is designed to support a primary pipe within a secondary containment pipe in a double containment piping system, while allowing either pipe to move in specific directions within prescribed limits. This combination of features is useful when used in a specially designed double containment expansion loop, offset or directional change assembly where flexibility at the elbows is required. It is also useful in conjunction with underground double containment piping systems, in order to allow the proper deflection of the secondary containment piping in order to resist burial loads superimposed upon it. Since the majority of double containment piping systems are underground, and those that are aboveground are likely to require expansion assemblies, this has important utility in such systems.
The support can be designed as a series of independent supports, or with the top and bottom portions consisting of continuous profiles, thereby providing continuous support of the primary piping system, and can even accommodate two side-by-side primary pipes.
When the support is designed from continuously extruded top and bottom profiles, the support in effect becomes a support system (as opposed to a series of independent supports) with the modular construction of a supporting system that is capable of supporting multiple primary pipes within a single secondary containment pipe, and the support will allow independent (unrestrained) movement of the primary pipes, thereby allowing for designs involving unevenly expanding/contracting multiple inner pipes.